1. Field of the Invention
This invention concerns a door and door mechanism for the head access opening in a cartridge containing a magnetic disc or the like, in which the door seals around the head access opening when closed and is prevented from inadvertently opening by a locking mechanism.
2. Prior Art
Sliding head access doors have been previously used in commercially available cartridges. The operating mechanism for these doors requires that an extension of the door be made flexible so that it can bend at 90.degree. around an opening mechanism. In this arrangement, there is considerable friction between the extension of the door and the track in which it runs, causing the door operation to be unreliable. Further, because the extension of the door is required to be flexible, the choice of materials for the door is thereby limited. Not only do these head access doors not provide good sealing, but it is possible to push the door open with a finger or thumb when the cartridge is out of the disc-drive unit and hence to allow the ingress of contaminants into the cartridge, there not being a locking mechanism to prevent this such as in the present invention.
In U.S. Pat. No. 4,045,821, a cartridge for tape which has a shutter with a self-locking mechanism is described. That locking mechanism makes use of a U-shaped detent 45 having pawls 49 which fit into recesses at 125 (FIG. 11A of that patent). However, the described arrangement substantially differs from the present invention.